The present invention relates to a semiconductor particle having a surface on which a methine dye is adsorbed. The invention also relates to a photoelectric material using the particles and a photoelectric conversion device using the material.
A photoelectric material (photovoltaic element) is used in various photosensors, copying machines and photovoltaic devices. The photoelectric materials are constructed according to a method using a metal as a photosensor, a method using a semiconductor as a photosensor, a method using an organic pigment or a dye as a photosensor or a complex method.
The semiconductor photosensor method uses semiconductor particles spectrally sensitized with a dye. U.S. Pat. Nos. 4,684,537, 4,927,721, 5,084,365, 5,350644, 5,463,057, 5,525,440 and Japanese Patent Provisional Publication No. 7(1995)-249790 disclose the semiconductor particles spectrally sensitized with a dye. The spectral sensitizing dyes used in the publications are usually ruthenium complexes, which are rather expensive.
Japanese Patent Provisional Publication No. 7(1995)-249790 further describes that a methine dye such as a cyanine dye or a merocyanine dye can be used as a spectral sensitizing dye for the semiconductor particles. The methine dye has been researched and developed as a spectral sensitizing dye for silver halide grains of a silver halide photo graphic material. Various methine dyes are practically used in a large scale in the technical field of the silver halide photography. Therefore, many methine dyes, which are inexpensive and excellent in optical characteristics are known in the silver halide photography.
In a silver halide photographic material, a methine dye is used as a spectral sensitizing dye, a filter dye, an antiirradiation dye or an antihalation dye. The silver halide photographic material is usually sensitive to a visible light to form a visible image. Therefore, the photographic methine dye usually has the maximum absorption within the visible wavelength region. However, the visible, light has a low photoelectric conversion efficiency.
An object of the present invention is to improve the photoelectric conversion efficiency.
Another object of the invention is to provide a semiconductor particle sensitized with an infrared wavelength. region.
A further object of the invention is to provide a photoelectric material and a photoelectric conversion device having a high photovoltaic effect.
A furthermore object of the invention is to provide a new methine dye having the maximum absorption within the infrared region.
The present invention provides a semiconductor particle having a surface on which a methine dye is adsorbed, wherein the methine dye is represented by the formula (I): 
in which Q1 is a tetravalent aromatic group; each of X1 and X2 independently is a single bond or xe2x80x94CR3xe2x95x90CR4xe2x80x94; when X1 is a single bond, Y1 is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94Sexe2x80x94, xe2x80x94NR5xe2x80x94, xe2x80x94CR6R7xe2x80x94 or xe2x80x94CR8xe2x95x90CR9xe2x80x94; when X1 is xe2x80x94CR3xe2x95x90CR4xe2x80x94, Y1 is a single bond; when X2 is a single bond, Y2 is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94Sexe2x80x94, xe2x80x94NR5xe2x80x94, xe2x80x94CR6R7xe2x80x94 or xe2x80x94CR8xe2x95x90CR9xe2x80x94; when X2 is xe2x80x94CR3xe2x95x90CR4xe2x80x94, Y2 is a single bond; each of R1 and R2 independently is an aliphatic group or an aromatic group; each of R3, R4, R5, R6, R7, R8 and R9 independently is hydrogen or an alkyl group; each of P1 and P2 independently is xe2x95x90L1xe2x80x94Bo, xe2x95x90L2xe2x95x90Ak or xe2x95x90L3xe2x80x94Ar; L1 is a methine chain having an odd number of methines; Bo is an onium form of a basic nucleus; L2 is a methine chain having an even number of methines; Ak is an acidic nucleus of a keto type; L3 is a methine chain having an odd number of methines; and Ar is an aromatic nucleus.
The invention also provides a photoelectric material comprising a conductive support and a light-sensitive layer containing semiconductor particles spectrally sensitized with a methine dye, wherein the methine dye is represented by the formula (I).
The invention further provides a photoelectric conversion device comprising a photoelectric material, a charge transfer layer and a counter electrode, said photoelectric material comprising a conductive support and a light-sensitive layer containing semiconductor particles spectrally sensitized with a methine dye, wherein the methine dye is represented by the formula (I).
The invention furthermore provides a methine compound represented by the formula (Va): 
in which each of X101 and X102 independently is a single bond or xe2x80x94CR103xe2x95x90CR104xe2x80x94; when X101 is a single bond, Y101 is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94Sexe2x80x94, xe2x80x94NR105xe2x80x94, xe2x80x94CR106R107xe2x80x94 or xe2x80x94CR108xe2x95x90CR109xe2x80x94; when X101 is xe2x80x94CR103xe2x95x90CR104xe2x80x94, Y101 is a single bond; when X102 is a single bond, Y102 is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94Sexe2x80x94, xe2x80x94NR105xe2x80x94, xe2x80x94CR106R107xe2x80x94 or xe2x80x94CR108xe2x95x90CR109xe2x80x94; when X102 is xe2x80x94CR103xe2x95x90CR104xe2x80x94, Y102 is a single bond; each of R101 and R102 independently is an aliphatic group or an aromatic group; each of R103, R104, R105, R106, R107, R108 and R109 independently is hydrogen or an alkyl group; each of X103 and X104 independently is a double bond or xe2x95x90CR113xe2x80x94CR114xe2x95x90; when X103 is a double bond, Y103 is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94Sexe2x80x94, xe2x80x94NR115xe2x80x94, xe2x80x94CR116R117xe2x80x94 or xe2x80x94CR118xe2x95x90CR119xe2x80x94; when X103 is xe2x95x90CR113xe2x80x94CR114xe2x95x90, Y103 is a single bond; when X104 is a double bond, Y104 is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94Sexe2x80x94, xe2x80x94NR115xe2x80x94, xe2x80x94CR116R117xe2x80x94 or xe2x80x94CR118xe2x95x90CR119xe2x80x94; when X104 is xe2x95x90CR113xe2x80x94CR114xe2x95x90, Y104 is a single bond; each of R111 and R112 independently is an aliphatic group or an aromatic group; each of R113, R114, R115, R116, R117, R118 and R119 independently is hydrogen or an alkyl group; each of the benzene rings A and B may be condensed with another benzene ring; and the benzene rings A, B and the condensed benzene rings may have a substituent group.
The invention still furthermore provides a methine compound represented by the formula (Vb): 
in which each of X121 and X122 independently is a single bond or xe2x80x94CR123xe2x95x90CR124xe2x80x94; when X121 is a single bond, Y121 is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94Sexe2x80x94, xe2x80x94NR125xe2x80x94, xe2x80x94CR126R127xe2x80x94 or xe2x80x94CR128xe2x95x90CR129xe2x80x94; when X121 is xe2x80x94CR123xe2x95x90CR124xe2x80x94, Y121 is a single bond; when X122 is a single bond, Y122 is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94Sexe2x80x94, xe2x80x94NR125xe2x80x94, xe2x80x94CR126R127xe2x80x94 or xe2x80x94CR128xe2x95x90CR129xe2x80x94; when X122 is xe2x80x94CR123xe2x95x90CR124xe2x80x94, Y122 is a single bond; each of R121 and R122 independently is an aliphatic group or an aromatic group; each of R123, R124, R125, R126, R127, R128 and R129 independently is hydrogen or an alkyl group; each of X123 and X124 independently is a double bond or xe2x95x90CR133xe2x80x94CR134xe2x95x90; when X123 is a double bond, Y123 is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94Sexe2x80x94, xe2x80x94NR135xe2x80x94, xe2x80x94CR136R137xe2x80x94 or xe2x80x94CR138xe2x95x90CR139xe2x80x94; when X123 is xe2x95x90CR133xe2x80x94CR134xe2x95x90, Y123 is a single bond; when X124 is a double bond, Y124 is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94Sexe2x80x94, xe2x80x94NR135xe2x80x94, xe2x80x94CR136R137xe2x80x94 or xe2x80x94CR138xe2x95x90CR139xe2x80x94; when X124 is xe2x95x90CR133xe2x80x94CR134xe2x95x90, Y124 is a single bond; each of R131 and R132 independently is an aliphatic group or an aromatic group; each of R133, R134, R135, R136, R137, R138 and R139 independently is hydrogen or an alkyl group; each of the benzene rings C and D may be condensed with another benzene ring; and the benzene rings C, D and the condensed benzene rings may have a substituent group.
The present inventors have found that the methine dye represented by the formula (I) has a large absorption within the infrared region. An infrared ray has a high photoelectric conversion efficiency, compared with the visible light.
The semiconductor particles can be strongly sensitized to the infrared ray by using adsorbing the methine dye represented by the formula (I) on the surface of the particles. A photovoltaic effect of a photoelectric material and a photoelectric conversion device are improved by using the semiconductor particles sensitized to the infrared ray. As a result, an inexpensive and excellent photoelectric material or photoelectric conversion device can be obtained by using the semiconductor particles of the present invention.